Clinical vs. laboratory identification of drugs of abuse in patients admitted for acute poisoning.

OBJECTIVE

The extent of drug abuse in patients admitted for self-poisonings is uncertain. The aim of this study was to assess the pattern of drugs of abuse among patients admitted for acute poisoning according to age and gender, and to study the concordance between the clinical assessments by the physicians on duty and the drug analyses.

METHODS

Prospective cross sectional study of all patients (n = 405, 52% males, median age 31 years) treated for acute poisoning in our department during one year (2001). The physician on-call classified type of drug of abuse by history and clinical assessment. This was later compared to urine and blood samples analysed for ethanol, benzodiazepines, opiates, cocaine, ecstasy, GHB, amphetamine and cannabis.

RESULTS

In 320 admissions (79%), the comparison between clinical diagnosis and laboratory analyses could be performed. A total of 478 drugs were suspected and 621 were found. The main toxic agents found were benzodiazepines (49.7%), ethanol (40.3%), opiates (35.3%), cannabis (23.8%) and amphetamine (21.3%). Ninety-two had used drugs of abuse. The agreement between clinical assessments and laboratory findings was best for GHB and ethanol (kappa = 0.43), and for opiates (k = 0.38). For benzodiazepines and cannabis, the concordance was poor (k = 0.18 and 0.10, respectively). However, the correct clinical evaluation for these substances was 59% and 77%, respectively.

CONCLUSIONS

Drugs of abuse were more frequently found than suspected clinically. Benzodiazepines, ethanol and opiates were most common. The agreement between clinical assessment and drug analyses was moderate to low. Physicians seem to underestimate the use of these drugs.